Heat exchanger with intermediate plate

ABSTRACT

The present invention relates to a heat exchanger, in particular, an oil cooler for motor vehicles, constructed from trough-shaped heat exchanger plates which are stacked into one another and from turbulence inserts, having two openings for one medium and two further openings for another medium in order to form collecting ducts for the supply and discharge of the media, with flow ducts for the media being formed between the heat exchanger plates. The heat exchanger also includes flow ducts connected to the associated collecting ducts, an upper closure plate which has convexities in the region of the collecting tanks, and an intermediate plate which is provided with holes. The intermediate plate is arranged between the closure plate and the uppermost heat exchanger plate, and one of the holes, formed as a pressure equalizing opening, interacts with the upwardly aligned convexity in the closure plate to improve the internal pressure stability.

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority is hereby claimed to German Patent Application No. DE 10 2007011 762.2, filed Mar. 10, 2007, the entire contents of which isincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a heat exchanger, such as an oil cooler, havinga connecting plate.

SUMMARY

DE 103 49 141 A1 discloses a plate heat exchanger constructed fromtrough-shaped heat exchanger plates which are stacked into one another.This type of heat exchanger is used in a vehicle as an oil cooler. Thepublication proposes a solution which can withstand internal pressuresof 6 to 10 bar. This is obtained by using an intermediate plate as a tierod which is inserted and soldered in between the closure plate and thefinal, uppermost turbulence insert. The intermediate plate has the samehole pattern as the turbulence insert which is soldered to it. Thestructural principle proposed there has the disadvantage that, at yethigher internal pressures, defects can occur, since the turbulenceplates are usually produced from metal sheets of very low wall thicknesswhich are restricted in terms of their resistance to extreme internalpressures. The known closure plate has convexities in the region of thecollecting ducts, which convexities are aligned substantially inward.

It is the object of the invention to further improve the resistance ofthe heat exchanger to internal pressure. The object is achievedaccording to the invention with the generic heat exchanger by means ofits refinement as explained in greater detail below.

Because the intermediate plate is arranged between the closure plate andthe uppermost heat exchanger plate, and because at least one of theholes therein interacts, as a pressure equalizing opening, with theupwardly aligned convexity in the closure plate, the heat exchanger isnow also suitable for internal pressures of considerably higher than 10bar. The pressure equalizing opening makes it possible, for example, forthe oil to enter into the space between the convexity and theintermediate plate and to impart a force there which counteracts theforce which acts between the heat exchanger plate and the intermediateplate. A certain pressure release is thereby obtained.

A pressure release is also obtained in that the closure plate isreplaced by a closure disk which has the convexity and which isconnected to the intermediate plate, with the diameter of the convexitybeing greater than the diameter of the collecting duct, with theintermediate plate being arranged on the uppermost heat exchanger plate.The alternative proposed solution therefore dispenses entirely with theclosure plate and uses merely a closure disc which is slightly largerthan the duct which it closes off. The size of the diameter of thepressure equalizing opening D is in the range from 1 mm to 10 mm,preferably in the range from 1 mm to 2 mm.

The closure plate and the intermediate plate can have differentthicknesses a and z. The values are in the range of 1 mm to 3 mm for thethickness a and in the range from 1 mm to 2 mm for the thickness z.

The convexities in the closure plate have a greater diameter than thecollecting ducts of the media.

An alternative or additional possibility for increasing the internalpressure stability is to design the penultimate turbulence plate, whichis situated in the flow duct of the one medium, in such a way that itdoes not have an opening like the other turbulence plates. A preferablysmall hole which has the function as a pressure equalizing opening canhowever be provided in the turbulence plate in the region of thecollecting tank.

The lowermost heat exchanger plate is formed from a thicker metal sheetthan the other heat exchanger plates. The fastening plate is also of atleast two-part design.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

DESCRIPTION OF THE DRAWINGS

The invention is now briefly described in various exemplary embodimentswith reference to the appended drawings.

FIG. 1 shows a section through an embodiment of the heat exchanger ofthe present invention.

FIG. 2 shows an enlarged detail from FIG. 1.

FIG. 3 shows a section through an alternative embodiment of the heatexchanger of the present invention.

FIG. 4 shows an enlarged detail from FIG. 3.

FIG. 5 shows a plane view of the intermediate plate.

FIG. 6 shows a sectional view of an alternative embodiment of the heatexchanger of the present invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

The basic design of the heat exchanger is described with respect toFIGS. 1-3. The heat exchanger is a plate heat exchanger, in particularan oil cooler 1. The latter is constructed from trough-shaped heatexchanger plates 10 which are stacked into one another and which bearagainst one another with their edges 100. Constantly alternating flowducts 8 and 9 for the two media (e.g., oil 8 and coolant 9), are formedbetween in each pair of heat exchanger plates 10. The heat exchangerplates 10 are identical and are stacked on top of one another, rotatedthrough 180°, in order to form the heat exchanger.

Circular openings 21, 31 are provided in the heat exchanger plates 10.The openings 21, 31 are provided with projecting edges 101, 102. Theprojecting edges 101, 102 bear against one another and thereby definethe collecting ducts 20 and 30 for the two media, which collecting ducts20 and 30 are hydraulically connected to the associated flow ducts 8 and9. Turbulence inserts 5 are arranged in the flow ducts 8, 9 between twoheat exchanger plates 10. Other turbulence-generating means, such as forexample knobs, beads or the like, could also be inserted into the flowducts 8 and 9, which are not shown here. The lowermost heat exchangerplate 13 is produced from a thicker metal sheet of approximately 2 to 5mm thickness. In this manner, the heat exchanger 1 is more stable athigh internal pressures and occurring vibrations.

The two exemplary embodiments show a fastening plate 14(a+b) which is oftwo-part design but can also be of single-part or three-part design.Inlet and outlet openings 25, 35 for the two media are situated in saidfastening plate 14, which media are in this case conducted into and outof the heat exchanger 1 through the fastening plate 14. The connectingpipes for the two media can alternatively or also be formed on the upperclosure plate 12 (not shown). The edge of the closure plate 12 isideally soldered to the edge 100 of the uppermost heat exchanger plate10. For this purpose, the edge 100 can be formed by bending or by meansof chamfering/beveling, so that the edge 100 is approximatelyform-fitting with respect to the edge 100 of the uppermost heatexchanger 10.

FIGS. 1 and 2 show the first embodiment. An additional intermediateplate 11 is placed between the uppermost heat exchanger plate 10 and theclosure plate 12. During soldering, the intermediate plate 11 is thenconnected to the adjacent plates. The closure plate 12 sealingly closesoff the four collecting ducts 20 and 30 of both media. Above thecollecting ducts 30 which collect one medium (e.g., oil) at least oneconvexity 6 is formed upward or outward in the closure plate 12. In theintermediate plate 11 situated below the latter, in each case one hole 3is situated above the collecting ducts 20 of the other medium, whichhole 3 is large enough to hold the projecting edge 101 of the opening 21of the uppermost heat exchanger plate 10.

Situated in the intermediate plate 11 above the collecting ducts 30 ofone medium is another hole 2 whose diameter D is less than or equal tothe diameter d of the collecting ducts 30. The diameter D is ideally inthe range from 1 to 10 mm, though a very small hole 2 which does notclose up during soldering is sufficient. The stresses which act areconducted outward via the intermediate plate 11 into the region outsidethe collecting ducts 30. The uppermost turbulence insert 5 in particularis protected. This is because, at high internal pressures in the rangeof 10 to 15 bar or more, the uppermost turbulence insert 5 would,without the intermediate plate 11, be torn open by the occurringstresses. In addition, the shape of the convexities 6 in the closureplate 12 ensures that the occurring forces are conducted outwardly moreeffectively. The diameter AP of the convexity 6 is therefore greaterthan the diameter d of the collecting ducts 30.

FIG. 5 shows a plan view of the intermediate plate 11. The figure is asimplified sketch. It is possible to see an edge region with the holes 2and 3. It can be clearly seen that the diameter D of the hole 2 in theintermediate plate 11 is ideally significantly smaller than the diameterd of the collecting duct 30. In particular, the shape of the hole 2 inthe intermediate plate 11 can be freely selected, but is preferablycircular or oval.

FIGS. 3 and 4 show an additional or alternative possibility of how theheat exchanger 1 can be yet more stable with respect to high internalpressures of one medium (e.g., oil). Here, the penultimate turbulenceinsert 5 in the upward direction is changed in the region of thecollecting ducts 30, specifically in such a way that the turbulenceinsert 5 is not provided with an opening 31 in the region of thecollecting ducts 30 but rather is of continuous design. Such turbulenceinserts 5 are, as is known, corrugated sheets, in that the corrugationsof which are provided incisions or the like which make it possible forthe medium to flow through them (not shown). The measure contributes tothe forces being distributed between the various heat exchanger plates10 and turbulence inserts 5 yet more effectively. The turbulence insert5 can however be provided with a pressure equalizing opening in theregion of the collecting duct 30.

FIG. 6 shows a heat exchanger which does not have a closure plate 12 butrather has, in its place, merely a circular closure disk 60 which lieson and is soldered to the intermediate plate 11. The closure disk 60 isslightly larger in diameter than the collecting duct 30. The closuredisk 60 has a convexity 6, whose diameter is slightly larger than thecollecting duct 30, and in the centre of the convexity 6, an inwardlyaligned convexity 61. Here, too, the intermediate plate 11 lies on theuppermost heat exchanger plate 10. Since the intermediate plate 11 isthinner than a closure plate, the weight of the heat exchanger isreduced. The thickness of the closure plate 60 can correspond to thethickness of the intermediate plate 11 since the convexity 6 ensuresstiffness.

Various features and advantages of the invention are set forth in thefollowing claims.

1. A heat exchanger, in particular an oil cooler for motor vehicles, theheat exchanger comprising: a plurality of trough-shaped heat exchangerplates which are stacked into one another, each of the plurality of heatexchanger plates having two openings for one medium and two furtheropenings for an other medium in order to form collecting ducts for thesupply and discharge of the one media and the other media; flow ductsfor the media being formed between the heat exchanger plates, the flowducts being connected to the associated collecting ducts; turbulenceinserts arranged in the flow ducts; an upper closure plate which hasconvexities adjacent at least one of the collecting ducts; and anintermediate plate which is provided with holes; wherein theintermediate plate is arranged between the closure plate and anuppermost heat exchanger plate, and wherein one of the holes interacts,as a pressure equalizing opening, with the upwardly aligned convexity inthe closure plate.
 2. The heat exchanger according to claim 1, whereinthe upwardly aligned convexities of the closure plate have aspherical-cap-like profile.
 3. The heat exchanger according to claim 2,wherein the upwardly aligned convexities of the closure plate have alarger diameter than the collecting ducts.
 4. The heat exchangeraccording to claim 1, wherein a diameter of the holes in theintermediate plate is significantly smaller than a diameter of thecollecting tank.
 5. The heat exchanger according to claim 4, wherein thediameter of the holes is between about 1 mm and about 2 mm.
 6. The heatexchanger according to claim 1, wherein the closure plate and theintermediate plate have different thicknesses.
 7. The heat exchangeraccording to claim 6, wherein the thickness of the closure plate isbetween about 1 mm and about 3 mm and the thickness of the intermediateplate is between about 1 mm and about 2 mm.
 8. The heat exchangeraccording to claim 1, wherein at least one of the turbulence inserts, ina region of the collecting tank in which the pressure equalizing openingis situated, is formed without an opening.
 9. The heat exchangeraccording to claim 8, wherein the turbulence insert includes at leastone pressure equalizing opening.
 10. The heat exchanger according toclaim 1, wherein a lowermost heat exchanger plate is formed from athicker metal sheet than the other heat exchanger plates.
 11. The heatexchanger according to claim 1, further comprising a fastening plate ofat least two-part design.
 12. The heat exchanger, in particular oilcooler for motor vehicles, the heat exchanger comprising: a plurality oftrough-shaped heat exchanger plates stacked into one another and havingtwo openings for one medium and two further openings for an other mediumin order to form collecting ducts for the supply and discharge of theone media and the other media; turbulence inserts; flow ducts for themedia formed between the heat exchanger plates and connected to theassociated collecting ducts; an intermediate plate which is providedwith holes; and a closure disk in the region of the collecting ducts andhaving a convexity which is connected to the intermediate plate; whereina diameter of the convexity is greater than a diameter of the collectingduct, and wherein the intermediate plate is arranged on an uppermostheat exchanger plate.
 13. The heat exchanger according to claim 12,wherein an inwardly aligned convexity is provided in a center of theconvexity.